AG Boch Research Focus

Bacterial plant pathogens and their weapons.

Two organisms fight to survive. The prokaryote aims to acquire nutrients whereas the eukaryote aims to protects the integrity of its cells.

Plants are well able to defende themselves and only specialized pathogens can colonize them. These pathogens have evolved sophisticated molecular weapons. Pseudomonas syringae and Xanthomonas bacteria use a type III secretion system (T3SS) to inject ca. 30 different effector proteins into plant cells (Fig. 1). These effectors sabotage the host cell from within (Fig. 2) and we study their molecular activities.

Genome Editing

We have cracked the code how TALEs recognize DNA-sequences. They bind DNA via a central repeat domain. Each repeat recognizes one bp via two amino acids (called RVD) (Fig. 4). Different RVDs recognize different bases and different TALEs contain different arrangements of repeats. This modularity has been a breakthrough for biotechnology, because it allows to design artificial proteins with any desired DNA-binding specificity.

Fig. 4: DNA-binding specificity of TALEs. Each 34-amino acid-repeat binds to one DNA bp and the amino acids at position 12 and 13 in each repeat determine specificity.

Genome editing is a technique to specifically modify any sequence in a eukaryotic cell. This method holds great prospects for targeted breeding in agriculture and livestock, personalized medicine, and a cure to heritable genetic disorders in humans.

TALENs (TALE-nuclease fusions) and CRISPR/Cas (Fig. 5) are very recently developed tools that have heralded a new age for genome editing with worldwide interest. We explore these techniques to develop plants with elevated pathogen resistance and other beneficial traits.